This application is directed to the use of additive concentrations of neutralized and/or acidified metallic hydrocarbyl sulfonate/mercaptothiazole reaction products and lubricant compositions containing same.
Metallic aryl sulfonates such as calcium dinonylnaphthalene sulfonates have been widely used in petroleum and synthetic lubricants as rust and corrosion inhibiting additives. Additionally, these and related metallic aryl sulfonates have, on occasion, provided good detergency and demulsibility properties in a variety of lubricant formulations.
Various reaction products of mercapto- and dimercaptothiadiazoles have been known to possess extreme pressure/antiwear properties, as exemplified in U.S. Pat. No. 4,661,273,; 4,382,869; and 4,678,592.
Accordingly, the use of metallic aryl sulfonates as rust inhibitor, corrosion inhibitor, and/or demulsifier additives in lubricants and greases is well known as is the use of mercapto- and dimercaptothiadiazoles for their extreme pressure/antiwear properties.
Lubricants in service applications often generate acid species or acid-forming species, especially when exposed to high operating temperatures, extended service life and/or contact with atmospheric oxygen during aeration caused by churning or moving elements of the lubricated machine. Acid-forming species can also be formed via hydrolysis or other similar mechanisms.
If metallic aryl sulfonates are used as additives in such systems described above, neutralization or acidification to form sulfonic acids can occur. If both metallic aryl sulfonates and dimercaptothiadiazole are used together in a lubricant, or alternatively pre-reacted in the presence of small quantities of organic or inorganic acids, the resulting products exhibit excellent lubricating properties in conjunction with good antioxidant, antiwear, antirust, and corrosion inhibiting performance, with potential antifatigue, cleanliness, thermal stabilizing and/or friction modifying properties.
The use of reaction products of acidified sulfonates and dimercaptothiadiazoles as multifunctional additives has not been reported in any literature known to applicants and is, therefore, believed to be novel. The composition of matter, the lubricant compositions containing such additives, and the use of such reaction products in lubricants to improve the performance properties are all believed to be unique and heretofore unknown.